Sewage

A preserved medieval waste pipe in Stockholm Old Town used to guide sewage onto the street where rain eventually would carry it away.

Sewage is the mainly liquid waste containing some solids produced by humans which typically consists of washing water, faeces, urine, laundry waste and other material which goes down drains and toilets from households and industry. It is one type of wastewater, and is a major actual or potential source of pollution especially in urban areas. Sewage services exist to manage sewage by collection, treatment and recycling or safe disposal into the environment. As of 2004 in the U.S., 850 billion gallons of raw sewage are being dumped into waterways every year.

History

According to Teresi et al. (2002):

The Indus architects designed sewage disposal systems on a large scale, building networks of brick effluent drains following the lines of the streets. The drains were seven to ten feet wide, cut at two feet below ground level with U-shaped bottoms lined with loose brick easily taken up for cleaning. At the intersection of two drains, the sewage planners installed cesspools with steps leading down into them, for periodic cleaning. By 2700 B.C., these cities had standardized earthenware plumbing pipes with broad flanges for easy joining with asphalt to stop leaks.

The first sanitation system have been found at the prehistoric Middle East and the surrounding areas. The first time an inverted siphon system was used, along with glass covered clay pipes, was in the palaces of Crete, Greece. It is still in working condition, after about 3000 years. The system then remained with not much progress until the 16th century, where, in England, Sir John Harington invented a device for Queen Elizabeth (his Godmother) that released wastes into cesspools.

Sewage services

Collection and disposal

Main article: Sewage collection and disposal

A system of sewer pipes (sewers) collects sewage and takes it for treatment or disposal. The system of sewers is called sewerage or sewerage system (see London sewerage system) in UK English and sewage system in US English. Where a main sewerage system has not been provided, sewage may be collected from homes by pipes into septic tanks or cesspits, where it may be treated or collected in vehicles and taken for treatment or disposal. Properly functioning septic tanks require emptying every 2-5 years depending on the load of the system.

Treatment

Main article: Sewage treatment

Sewage treatment is the process of removing the contaminants from sewage to produce liquid and solid (sludge) suitable for discharge to the environment or for reuse. It is a form of waste management. A septic tank or other on-site wastewater treatment system such as biofilters can be used to treat sewage close to where it is created.

Sewage water is a complex matrix, with many distinctive chemical characteristics. These include high concentrations of ammonium, nitrate, phosphorus, high conductivity (due to high dissolved solids), high alkalinity, with pH typically ranging between 7 and 8. Trihalomethanes are also likely to be present as a result of past disinfection.

In developed countries sewage collection and treatment is typically subject to local, state and federal regulations and standards.

Facts about sewage

• The words 'sewage' and 'sewer' come from Old French seuwiere or from Anglo-Norman sewere or from Anglo-French assewer, essiver meaning "(channel) to drain the overflow from a fish pond" or "to drain" and ultimately from Vulgar Latin *exaquare or *exaquria, from Latin ex- ‘out of’ + aqua ‘water’.[1]
• The words 'sewerage' and 'sewage' were used interchangeably (but wrongly) in the past. This use is correct in US English.[2][3]

See also

• Drainage system
• Ecological sanitation
• Humanure
• ISO 5667
• ISO 10304
• Jenkem
• Sanitary sewer overflow
• Sewage pumping
• Waste management
• Water quality

External links

• Sewer History - main focus is sewers, but also contains significant information on sewage, sewage treatment and disposal, and health impacts.
• A tour of the Everett Water Pollution Control Facility in Washington, written by an employee.
• Website of the Technische Universität Darmstadt and the CEEP about Phosphorus Recovery